Electrode for gaseous discharge tubes



June 20, 1933. F. B. HALE 1,915,186

ELECTRODE FOR GASEOUS DISCHARGE TUBES Filed Nov. 9, 1929 INVENTOR. F- El. HFILE A TTORNEYS.

Patented June 20, 1933 FRANK B. HALE, OF SAN FRANCISCO, CALIFORNIA ELECTRODE FOR GASEOUS' DISCHARGE TUBES Application filed November 9, 1929. Serial No. 406,042.

This invention relates to improvements in electrodes and has particular reference to an electrode for use with gaseous illuminating signs, such as the neon light.

The principal object of the invention is to produce an electrode Which will have a longer life, and one which will not sputter and give off a deposit onto the glass of the tube.

A further object is to produce an electrode which will stand a much higher current than is now possible with the ordinary electrode.

A further object is to produce an electrode which will cause a lower voltage drop across the terminals of the tubes.

A still further object is to produce a terminal which will permit a longer length of tube for each transformer used.

Other objects and advantages will be apparent during the course of the following description.

In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like 2 parts throughout the same,

Figure I is a fragmentary side elevation of a tube having-my electrode therein,

Figure II is a vertical cross section through Figure I, and

Figure III is a cross sectional view taken on the line 3-3 of Figure II.

At the present time it is common to use in gaseous signs an electrode such as a lava-tip having a metal electrode deposited therein or merely an iron electrode, but it has been found that these forms of electrodes will not stand the high current necessary to remove the particles of foreign substances which are deposited upon the glass of the tube in which the electrode is being used, without causing an excessive heating of the tube adjacent the electrode with a consequent serious result such as the depositing onto the tube of some of the matter given off by decomposition of the electrode or the softening and collapse of the walls of the tube under atmospheric pressure against the vacuum within the tube. I have therefore devised an electrode which overcomes all of these disadvantages.

In the accompanying drawing wherein for the purpose of illustration is shown a preferred embodiment of my invention, the numeral 5 designates the end of a glass tube such as commonly employed in neon signs. At the end of this tube is attached a bulb 6 within which is sealed as at 7 an electrode terminal 8. It is at this terminal that I provide my electrode 9 which is preferably counter-bored as at 11 so as to provide a concentrated electronic emission of ring-like 60 form in contradistinction to an area. This electrode 9 is formed in the following manner.

A short piece of relatively pure iron is first immersed for approximately 24 hours 66 in an acid bath for the purpose of removing any grease or. other foreign substances from its surface. The electrode is then removed from the acid bath and immersed in a bath consisting of approximately eighty percent 70 (80%) strontium nitrate and substantially twenty percent (20%) zirconium nitrate and after dipping in this bath the electrode is heated in a Bunsen flame to substantially a white heat. This causes the strontium and zirconium salts to be deposited on the surface of the electrode and by repeated clippings and heating, a substantial deposit is rapidly built up upon the surface of the electrode.

After the electrode has been thus conditioned it is placed within the bulb and sealed therein. Now assuming that the same has been attached to a tube, the tube is connected to the evacuating pump and while being evacuated a current is passed through the tube, the purpose of which is to heat the tube to a degree wherein the glass will give off any matter which it may have adhering to its surface, and as this current is considerable it is evident that the electrode must be able to withstand it without breaking down and giving off injurious gases which would shorten the life of the tube.

I have found that my electrode constructed in accordance with the above will perform all the functions herein set forth.

It is to be understood that the form of my invention herewith shown and described is to be taken as a preferred example of the same and that various changes relative to the material, size, shape and arrangements of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described my invention, I claim 1. The method of making an electrode for a gaseous tube comprising taking an iron basc, dipping the same in a bath of nitrates of strontium and zirconium and then applying heat to convert the nitrate into an oxide.

2. The method of making an electrode for a gaseous tube, comprising taking an iron base, dipping the same repeatedly in a bath consisting of substantially of strontium nitrate and 20% zirconium nitrate to form a deposit upon the iron base, and then heating the same to convert the nitrate into an oxide.

3. The method of making an electrode for a gaseous tube comprising taking a metal base, coating the end thereof with an oxide of metal of the earth alkali group, and removing the coating from the central portion of the end to leave a ring-like active surface.

In testimony whereof I aflix my signature.

FRANK B. HALE. 

